1. Technical Field
On a floating vessel there is need for a system, which supplies sea water for various uses onboard. There are various aspects to such sea water systems and also to the vessels, on which the systems are arranged.
2. Background
On a floating vessel sea water, i.e. water ambient of the floating vessel, is used in many applications, such as ballasting, fire-fighting and as a cooling fluid. The floating vessel must have a suitably arranged system for supply of sea water. Requirements on such sea water systems are: high dependability, low risk of leakage, high priority consumers of sea water such as a fire fighting system must be prioritized over lower priority users, low susceptibility to damage, easy maintenance.
A floating vessel, such as a ship or a semi-submersible vessel, is often provided with one or more ballast systems in order to control the draught and/or the inclination of the floating vessel. Generally, a ballast system comprises a ballast tank, and in practice, often a plurality of ballast tanks. A ballast tank is adapted to be filled with sea water and when it is to be emptied, the sea water often is directed back to the ambient environment.
GB 2169864 discloses a ballast arrangement including a sea-chest, to which a pump is connected for pumping sea water through a conduit to a level above an uppermost ballast tank. From this level the sea water is distributed through a conduit to different ballast tanks. When a ballast tank is emptied the sea water is directed from the ballast tank back to the pump, which now is used for pumping the sea water overboard.